Polymer latex for ultraviolet absorbtion on fabric

ABSTRACT

A process for the production of an ultra violet absorbing polymer latex is provided. The inventive process involves the emulsion polymerization of a benzotriazole- or benzophenone-containing monomer with a vinyl functional monomer in the presence of a chain transfer agent, preferably 1-dodecanethiol. The latex provides excellent long-lasting, easy to apply, difficult to remove, ultraviolet absorption properties for many different substrates, most notably fabrics. Different articles and fabrics coated, covered, laminated, and the like, with the inventive latex are also provided.

FIELD OF THE INVENTION

This invention relates to a polymer latex which provides excellentlong-lasting ultraviolet absorption and colorlightfastness when appliedto myriad substrates, notably plastics and fabrics. The inventive latexcomprises benzotriazole or benzophenone monomers copolymerized withacrylic acid comonomers, all of which are subjected to a chain transferagent during emulsion polymerization. The resultant latex obtainsexcellent long-lasting ultraviolet absorption characteristics and iseasy to apply to and difficult to remove from fabrics, thus providing acost-effective improvement over the prior art. Moreover, the inventioncovers fabrics treated with the inventive polymer latex, particularlythose fabrics which have undergone supersonic air post-treatment. Theresultant articles to which the inventive latex is applied are alsocontemplated within this invention.

BACKGROUND OF THE PRIOR ART

The risks posed by ultraviolet radiation have become noteworthy inrecent years as concerns over environmental issues, particularly thethinning of the earth's protective ozone layer, increase. For instance,incidences of skin cancer due to overexposure to solar radiation andthus harmful ultraviolet rays have been on the rise. Ultraviolet (UV)radiation which has proven harmful to human skin includes the twodifferent types known as UV-A, which falls within the range of 320-400nm along the light spectrum, and UV-B, which is between 290-320 nm inwavelength. Any manner of reducing or preventing transmission of UVlight thus must effectively block or absorb such radiation between thesewavelengths (290 and 400 nm).

Ultraviolet radiation also affects the color of certain substrates byinitiating degradation of dyes, colorants, pigments, and the like.Long-term exposure to direct sunlight eventually results in a loss ofcolor or, at the least, a noticeable decrease in color strength. Sucheffects are particularly problematic within the automotive upholsteryand drapery industries since the colored surfaces, car seats andcurtains, are potentially exposed to ultra violet radiation for a greatdeal of time.

Sun protective compositions for direct contact with skin and coloredsurfaces have been developed in order to better prevent the damagingresults from such overexposure. For instance, PABA, or para-aminobenzoicacid, is a popular UV blocking (or absorbing) compound which may beincorporated into a composition, such as a tanning lotion for skin, or acoating composition for car seats, and the like. This compoundeffectively absorbs the harmful radiation within the ultraviolet rangeof frequencies such that the user's skin or subject substrate is notfully exposed to such light. Recently, a new ultraviolet protectivefactor (UPF) test has been developed and adopted by the AmericanAssociation of Textile Colorists and Chemists (AATCC) which provides amore thorough measurement of the ultraviolet absorption capabilities ofspecific fabrics within both the UV-A and UV-B wavelength ranges. Thismethod, AATCC Test Method 183-1998 determines the ultraviolet radiationblocked or transmitted by textile fabrics intended to be used for UVprotection. By utilizing a spectrophotometer or spectroradiometer, theUPF is calculated as the ratio of the erythemally (with erythema beingthe measurement of abnormal redness of skin due to ultraviolet radiationexposure) weighted ultraviolet radiation (UV-R) irradiance at thedetector with no specimen present as compared to the UV-R irradiancewith a specimen present, both over a range of wavelengths measured inintervals. This AATCC Test Method also measures Solar SpectralIrradiance through the subject fabric.

In order to decrease ultraviolet transmissions through clothing, pastdevelopments have provided protective measures from such harmfulradiation through the introduction of certain compounds into or ontoapparel fabrics. The prior art representative of this technologyincludes U.S. Pat. Nos. 4,857,305 to Bernhardt et al., 5,458,924 toKashiwai et al., and 5,637,348 to Thompson et al, as well as UnitedKingdom Patent 889292 to American Cyanamid. Furthennore, certain typesof weaves, twists, or bends of yarns or fabrics have been developedwhich effectively screen a wearer's skin from ultraviolet radiation.Such technology is represented within the prior art through U.S. Pat.No. 4,861,651 to Goldenhersh. With such chemically treated or physicallymodified fabrics, a wearer could then cover his or her skin moreeffectively solely through adorning themselves with such sun protectiveapparel. However, the prior art modified fabrics still permittransmission of relatively high levels of UV transmission and areexpensive to produce. In order to decrease the potential colordegradation for substrates due to ultra violet exposure, UV-absorbingcopolymer latices have been utilized, most notably as films, coatings oradhesives. Such latices have provided, for example, a barrier topotentially damaging ultraviolet rays, both to a coated article and to,if such an article comprises apparel, a wearer of such an article.Polymer UV absorbing latices for textiles thus generally provide abeneficial, cost-effective protective alternative to higher density andhigher costing fabrics.

Ultraviolet absorbing polymer latices incorporating UV-absorbingmonomers and vinyl-functional comonomers have been disclosed within theprior art. However, nowhere has the novel procedure of emulsionpolymerization of at least two monomers, all in the presence of a chaintransfer agent, most notably 1-dodecanethiol, been taught, fairlysuggested, or practiced. Past polymer UV absorbing latices include thosetaught within U.S. Pat. No. 5,629,365, to Razavi, entirely incorporatedherein by reference. Such polymer latices comprise the same comonomersas in the instant, namely benzotriazole- and/or benzophenone-containingmonomers polymerized with vinyl functional monomers; however, patenteeboth requires that the final product be subject to cross-linking, as isunnecessary within the inventive latex, and fails to mention or fairlysuggest the presence of a chain transfer agent. Also of note as priorUV-absorbing polymer latices are those products taught within U.S. Pat.No. 4,528,111, to Beard et al., also herein entirely incorporated byreference. These polymers comprise the same benzotriazole comonomers asin the present invention; however, such latices are not formed of thesame vinyl-functional comonomers, or through the same emulsionpolymerization in the presence of a chain transfer agent as within theinventive latex. Patentee's latices are made through a solutionpolymerization process which includes the utilization of environmentallydamaging solvents. Furthermore, the requisite solvents used withinsolution polymerization procedures are known to adversely affect subjectsubstrates, particularly textiles, through dissolving dyes andcolorants, hindering lightfastness by plasticizing finishes on textiles,and degrading polymer coatings. As a result, solution polymerization isan highly undesirable method of producing a stable polymer latex, again,particularly for textile substrates.

Other prior U.S. patents disclose similar compositions and procedures asthose mentioned above; however, again, there is no prior teaching of theinventive process utilizing a chain transfer agent during an emulsionpolymerization in order to form an UV-absorbing polymer latex. Such U.S.Patents which teach the polymerization of an UV-absorbing monomer with avinyl functional comonomer include 3,429,852, to Skoultchi, 3,745,010,to Janssens et al., 3,761,272, to Mannens et al., 4,443,534, to Kojimaet al., 4,455,368, to Kojima et al., 4,612,358, to Besecke et al.,4,652,656, to Besecke et al., 5,099,027, to Vogl et al., and 5,459,222,to Rodgers et al., all herein entirely incorporated by reference.

Even with all the previous work performed in this crowded area, therestill remains a great need to produce a long-lasting, lightfast, stable,hard to remove, easily handled, and cost-effective ultraviolet-absorbing polymer latex for application to certain surfaces inorder to act as a barrier against potentially damaging penetrative UVrays.

DESCRIPTION OF THE INVENTION

It is therefore an object of this invention to provide a UV-absorbingpolymer latex which produces optimum colorlightfastness performance ondifferent substrates and effectively prevents color degradation throughUV exposure to different substrates, including fabrics and polymericfilms and composites. Also, it is an object of this invention to provideoptimum UV-absorption performance for the inventive polymer latexthrough the manipulation of the specific latex monomer/comonomer ratios.Furthermore, an object of the invention is to provide the most reliable,best performing, easily adhering, and semi-permanent UV-absorbingpolymer latex through the utilization of emulsion polymerization, andmore particularly semi-batch emulsion polymerization, in the presence ofa chain transfer agent. Additionally, it is an object of the inventionto improve the overall performance of the inventive polymer latex byadjusting the post-polymerization surface tension of the latex to anoptimum level on the subject substrate. Yet another object of theinvention is to provide an improved UV-absorbing coating for fabrics,with improved UV-absorption and colorlightfastness, in comparison tothose taught within the prior art which comprise the same type andamount of UV-absorbing monomer and vinyl-functional comonomer. Still afurther object of the invention is to provide improvedcolorlightfastness and UV absorption for a pile fabric substrate bycoating the substrate with the inventive latex and subsequently exposingthe coated substrate to a supersonic air post-treatment.

Accordingly, this invention concerns a method of making an ultra violetabsorbing copolymer latex by emulsion polymerization comprising

mixing together, in the presence of at least one polymerizationinitiator and at least one chain transfer agent,

(a) at least one monomer having at least one ultra violet absorbingfunctionality selected from the group consisting essentially ofbenzotriazole, benzophenone, and mixtures thereof; and

(b) at least one monomer having at least one vinyl functionality.

Also, the invention concerns articles made therefrom and such articlespretreated with supersonic air applications.

Nowhere within the prior art has such a specific method of producing anUV-absorbing polymer latex utilizing both emulsion polymerization and achain transfer agent been disclosed, practiced, or fairly suggested.Such a method provides a significant advantage over the solutionpolymerized and merely cross-linked (and not subjected to any chaintransfer agent) latices of the prior art. Through the utilization of anemulsion polymerization process in conjunction with the presence of achain transfer agent, it has been determined that the inventive polymerlatex offers several novel and highly unexpected benefits. First, andmost notably, the inventive latex effectively absorbs UV radiation andprovides optimal colorlightfastness with a low amount of UV-absorbingmonomer and a high amount of acrylate comonomer, particularly whenapplied to fabrics. Generally, one of ordinary skill in this art wouldexpect that increased weight ratios of UV-absorbing monomer wouldimprove UV-absorption and colorlightfastness. Surprisingly, such abelief is not the case here.

Second, the production of the best performing UV-absorbing polymer latexhas been found to involve a manufacturing process utilizing a chaintransfer agent (and not a cross-linking agent) during emulsionpolymerization. Again, such a combination with the particular monomersand comonomers of the inventive latex produces the unexpectedimprovements in UV-absorbing properties and colorlightfastness,especially for fabric substrates. Chain transfer agents are unlikelycandidates as additives within the particular polymerization processessimply because one of ordinary skill in the art would expect longerchain polymers to provide better lightfastness and UV-absorbingcapabilities and chain transfer agents actually lower the degree ofpolymerization. Furthermore, such chain transfer agents are not normallyused in emulsion polymerizations.

Third, it has been found that colorlightfastness characteristics can beoptimized after polymerization upon producing the optimal surfacetension of the latex. The ability of a latex to coat a substrate ishighly dependent on the relative surface tension values of both thelatex and the subject substrate. In order to thoroughly coat the desiredsubstrate, then, it is necessary to modify the surface tension of thepolymer latex to closely equal the surface tension of the subjectsubstrate. The inventive polymer latex will generally obtain a muchhigher surface tension than that of the fabric or polymer film, asmerely examples, on which the latex to be coated. The surface tension ofthe inventive polymer latex may thus be modified through the addition ofwetting agents/surfactants in order to facilitate the desired coatingprocess. Water-soluble wetting agents are one class of surfactants whichmay be employed in this respect, including lower aliphatic alcoholsnonionic surfactants. The most preferred surfactants are those which arefluorinated, such as Zonyl™, available from DuPont, and Fluorad®,available from 3M. Some more examples of suitable surfactants as well asa further discussion of this aspect of the inventive method arepresented in U.S. Pat. No. 5,629,365, to Razavi, as entirelyincorporated herein by reference above.

Fourth, it has been found that the UV-absorbing monomer, whenpolymerized with the acrylate comonomer, and subsequently coated onto asubstrate surface, provides improved UV-absorption andcolorlightfastness when compared to coatings of conventional UVmonomeric absorbers utilized alone and at equivalent UV-absorbing groupconcentration (i.e., the same amount of UV-absorber of prior artcoatings as the amount of UV-absorbing monomer present in the inventivepolymer latex). Such a result is very surprising and unexpected,considering the relative inexpensive cost of acrylate comonomers ascompared to the cost for UV-absorbing monomers and/or compounds.

Last, it has been found that supersonic air post-treatment specialprocessing of pile fabrics coated with the inventive UV-absorbingpolymer latex improves colorlightfastness performance. Such supersonicair treatments include those disclosed in U.S. Pat. No. 4,837,902, U.S.patent applications Ser. Nos. 08/593,670 and 08/999,638, and PCTApplication PCT/US97/16,415, all to Dischler. Such treatments allow theindividual pile fibers to “stand up” and/or open up improvingcolorlightfastness. The prior art teachings do not permit such extensiveand beneficial characteristics.

The resultant inventive polymer latex comprises at least oneUV-absorbing monomer and at least one vinyl functional comonomer.Generally, any proportions of these two constituents will provideeffective ultra violet protection and colorlightfastness. However, ithas been found that, surprisingly, ratios of amounts of the two monomersfrom about 10% UV absorbing monomer/90% vinyl functional comonomer toabout 85%/15%, provide optimum results with regard to the aforementioneddesired properties. From a colorlightfastness/cost effectivenessperspective, a more preferred range of ratios encompasses from about50%/50% to about 25%/75%. Most preferred, again from a position that theUV monomers are very expensive and colorlightfastness of the latex onthe fabric substrate is highly desired, is a range from about 40%/60% toabout 35%/65% UV monomer to vinyl-functional monomer. Improved ultraviolet protection seemingly would be afforded with a greater amount ofsuch a UV-absorbing monomer within the final polymer latex product;however, upon control of the final molecular weight distribution throughthe utilization of a chain transfer agent in a batch emulsionpolymerization process allows for lower amounts of expensiveUV-absorbing monomer to be used in order to obtain the most beneficialcharacteristics. As discussed further below, a batch procedure (whichentails the complete addition of all components simultaneously) providesunexpectedly favorable UV absorbing and lightfast characteristics ascompared to a polymer latex formed through a semi-batch process(periodic additions of components over time). Even so, the inventivelatex may be formed in any manner, with a batch procedure the preferredspecific method.

The inventive polymer latex also required a certain solids content topermit optimum results. In particular, a rather low level of solids isdesired. For instance, the entire polymer latex should have an averagesolids content (per individual polymer) of from about 15 to about 55%,preferably from about 20 to about 45%, and most preferably from about 25to about 33%. These levels provide beneficial convenience in handlingand resultant properties as well as better overall stability within thefinal polymer product.

Any benzotriazole- or benzophenone-containing vinyl-functional monomermay be utilized within the inventive polymer latex and method of makingsuch a latex as what is described as the UV-absorbing comonomer. Suchmonomers are well known as providing effective UV-absorption for myriadsurfaces, particularly on fabric substrates. The preferred UV-absorbingmonomer is 2-Hydroxy-5-acrylyloxyphenyl-2H-benzotriazole (sold byJanssen Pharmaceuticals under the tradename Norbloc 7966). Otherparticularly usefull specific UV-absorbing monomers within thisinvention include 1-(3-benzotriazol-2-yl-4-hydroxyphenyl)-ethyl esteracrylic acid (manufactured by Hoechst Celanese),2-(2-methacryloxy-5′-methylphenyl) benzotriazole (manufactured byPolysciences, Inc.), and 2-hydroxy-4-acrylyloxyethoxy benzophenone (soldunder the tradename Cyasorb™ UV-416 by Cytec, Inc.).

The vinyl-functional comonomer encompasses any non-UV functional group(benzotriazole, benzophenone, and the like) containing monomer having avinyl functionality. Any such monomer can be employed within thisinventive polymer latex; however, particularly preferred are those basedon acrylic acids, including acrylates and methacrylates, and mostparticularly the following: butyl methacrylate, butyl acrylate, methylmethacrylate, butyl methacrylate, ethyl-hexyl methacrylate, laurylmethacrylate, isodecyl methacrylate, methacrylic acid, and n-hexylmethacrylate. Most preferred is butyl methacrylate, particularly incombination with 2-Hydroxy-5-acrylyloxyphenyl-2H-benzotriazole. The useof any of these or mixtures of these comonomers is dependent upon thedesired stability and/or handling properties for the entire inventivepolymer latex.

The term chain transfer agent means a compound which functions both as apolymerization inhibitor and initiator. Basically, after polymerizationbegins, such a process continues either until the supply of availablemonomer is depleted or until some type of inhibitor acts upon thepolymerized compound. A chain transfer agent reacts with a polymerizedcompound by capping the reactive portion of the reactant (i.e.,comprises a free radical or an ionically charged moiety) therebyeffectively inhibiting polymerization of that one particular compound.However, such a chain transfer agent also has the ability to startpolymerization in a previously unreacted monomer by displacing anelectron or a leaving group. Such an agent is unique to additionpolymerization processes, especially within such processes utilizingbatch techniques. Any chain transfer agent may be utilized within theinventive method; however, preferred is 1-dodecanethiol. Other chaintransfer agents workable within this invention include, withoutlimitation, thiophenol, hydrophobic polymercaptans, and hydrophobichalogenated compounds. The chain transfer agent (CTA) should be presentin amounts of grams CTA per grams aggregate UV monomer andvinyl-functional monomer of from about 0.002 to about 0.050%; preferablyfrom about 0.008 to about 0.018%; and most preferably at about 0.0175%.

The polymerization initiator may be any of the well known compoundswhich perform such a function. For instance, peroxide, persulfate, andultra violet light are only a few of the many potential compounds andmanners of catalyzing the polymerization process within the inventivemethod. Preferred are coupled persulfate/bisulfites and azo(peroxides).

The textile fabric utilized within the inventive process may compriseany synthetic or natural fiber or blend of such fibers. As merelyexamples, and not intended as limitations, the textile fabric may beconstructed from fibers of polyester, nylon (−6 or −6,6), cotton,polyester/cotton blends, wool, ramie, lycra, and the like. The preferredsubstrate is made of polyester, and most preferably polyethyleneterephthalate yams. Also, the textile fabric may be of woven, non-woven,or knit construction. Knit is the most preferred.

The application of the latex to a substrate may be accomplished throughin situ formation of the inventive latex on the substrate surface orthrough any well known coating or impregnation procedure. Included,without any limitation intended, within this step are exhausting from aliquid formulation onto a fabric substrate, dipping/padding, knifecoating, spraying, roll coating, foam coating, and the like.Particularly preferred is an exhaustion procedure from a liquid to afabric substrate within a dye jet process.

To the subject substrate, any number of additives may be added eitherpre- or post-application of the inventive latex. For instance, when afabric substrate is utilized, any standard textile additives, such asdyes, colorants, pigments, softening agents, antioxidants, flameretardants, rheology agents, soil redeposition agents, and the like, maybe applied to the fabric surface. Cross-linking agents are not desiredwithin the inventive latex. Cross-linking, which is a totally differentprocess from chain transfer, would result in an uneven molecular weightdistribution within the inventive latex such that the desiredcolorlightfastness characteristics, as well as ease of handling andapplication, would not be attainable. Particularly desired as optionalfinishes to the inventive fabrics are soil release agents which improvethe wettability and washability of the fabric. Preferred soil releaseagents include those which provide hydrophilicity to the surface ofpolyester. With such a modified surface, again, the fabric impartsimproved comfort to a wearer by wicking moisture. The preferred soilrelease agents contemplated within this invention may be found in U.S.Pat. Nos. 3,377,249; 3,540,835; 3,563,795; 3,574,620; 3,598,641;3,620,826; 3,632,420; 3,649,165; 3,650,801; 3,652,212; 3,660,010;3,676,052; 3,690,942; 3,897,206; 3,981,807; 3,625,754; 4,014,857;4,073,993; 4,090,844; 4,131,550; 4,164,392; 4,168,954; 4,207,071;4,290,765; 4,068,035; 4,427,557; and 4,937,277. These patents areaccordingly incorporated herein by reference.

The inventive composite may be utilized for any substrate whichfunctions as a covering, particularly from sunlight, or which has asurface which is colored and subject to ultra violet radiationdegradation. As merely examples, then, the inventive latex may beapplied to apparel, automotive upholstery, furniture upholstery,drapery, napery, tents, awnings, plastic bottles and/or containers madefrom polypropylene, polyethylene, polyurethane, polyethyleneterephthalate, and mixtures thereof, and the like.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the inventive method and composition is setforth in the following EXAMPLES.

Production of the Inventive Latex

EXAMPLE 1

A dispersion of Norbloc™ 7966 (available from Janssen) was firstprepared with a sandmill in order to obtain an average particle size ofbelow 1 micron. 5 g. of Synfac® 8216 (available from Milliken Chemical),4 g. of Synfac® 8337 (available from Milliken Chemical), 6 g. Abex™ 18S(available from Rhône Poulenc), 0.5 g. Surfynol® TGE (available from AirProducts), and 300 g. deionized water were admixed in a beaker until thesurfactants all were dissolved. 120 g. of Norbloc™ 7966 were thenstirred into the solution and the entire solution was then poured into astirred, glass-lined sandmill. 550 g. of sand were then slowly added tothe sandmill and milled for 1 hour. The resultant dispersion was thenremoved and measured to constitute about 28% in solids. 85.7 g. of thedispersion were then added to a 125 ml. Erlenmeyer flask and diluted to100 g. with distilled water. In a second flask, 0.6 g Rhodacal® DS-10(available from Rhône Poulenc), 0.2 g Pluronic® F68 (available fromBASF), 0.6 g. of polyvinyl pyrrolidone K-90 (available from ISPTechnologies), and 0.2 g 1 -dodecanethiol (available from Aldrich) weredissolved in 50 g. distilled water. After dissolution, 36 g. of butylmethacrylate and 0.3 g methacrylic acid (both available from Rohm &Haas) were added and the second flask solution was stirred until astable emulsion was formed. This emulsion was then dilute further to 100g. with distilled water. In a third flask, 0.6 g Rhodacal® DS-10 and 0.3g Pluronic® F68 were dissolved in 100 g. distilled water. In separatevials, a catalyst solution comprising 0.04 g. sodium bisulfite(available from Aldrich) and an initiator solution of 0.04 g. ammoniumpersulfate (available from Aldrich) were dissolved in 6 g. distilledwater each.

The contents of the third flask were poured into a 1L reactor equippedwith a nitrogen inlet, thermometer, stirrer, and condenser with nitrogenoutlet. The reactor was heated to about 70° C., while being nitrogenpurged, for 30 minutes. A 1 ml. sample of the catalyst solution and a 1ml. sample of the initiator solution were each added to flasks 1 and 2,respectively, while stirring. 0.5 ml samples of each of the catalyst andinitiator solutions were also each added to the reactor. The contents offlasks 1 and 2 were then pumped into the reactor at a rate of 0.5ml/min. After 175 minutes, the addition of monomers was stopped andadditional 0.2 ml samples of both the catalyst and initiator solutionswere each added to the reactor. The temperature of the reactor was keptat 70° C. for 1 hour and then the reactor was allowed to cool. Thissemi-batch emulsion polymerization procedure yielded a 40 wt. % Norbloc7966/60wt. % butyl methacrylate UV-absorbing polymer emulsion with25-30% solids.

EXAMPLE 2

The UV-absorbing polymer emulsion from EXAMPLE 1 was diluted to obtain alatex comprising 2% solids (latex A). A drop of latex A was applied to apolyester film to test its wettability and it was found that latex Awould not wet the surface. The surface tension of latex A was thendecreased by dispersing 0.12% DuPont Zonyl™ FSN into the latex in orderto form a second latex sample, latex B. This dispersion was tested forits wettability and was found to indeed wet the surface of the subjectpolyester film indicating that the surface tension of latex B was lessthan or equal that of the polyester film (about 37-39 dynes/cm).

Application of the Inventive Latex to Various Substrates

EXAMPLE 3

The polymer latex of EXAMPLE 1 was then applied to fabric during a dyejet procedure. The latex was present in an amount of about 4% owf(roughly about 0.8% solids content owf) in the dye liquor. The remainingdye liquor components were as follows:

DYE LIQUOR COMPOSITION Component Amount (owf) Millex ® defoamer 9500.80% Synfac ® 9214 (surfactant) 0.08% Millitex ® DA-45 1.50% Millitex ®DA-50 1.50% Leveler 550 0.50% Acetic Acid (84%) 0.45% Hostalux ™ EBU1.00%

The fabric was a white-colored 100% polyester microdenier knit. Theratio of fabric to liquor was about 1:10. The dye liquor and fabric wereadded to the dye jet machine and subsequently heated. The machine washeated on a rising scale initially at a temperature of about 68° F.which was gradually raised 4° F. per minute until it reached 160° F.;then raised 3.5° F. per minute until it reached 240° F.; then 3° F. perminute until it reached 280° F. The machine was kept heated at atemperature of about 280° F. and then the temperature was lowered 3° F.per minute until it reached 140° F. The ultraviolet absorption wasmeasured for a sample coated with the inventive polymer latex as well asa control of uncoated fabric. UV absorption measurements were taken foreach wavelength from 300 to 400 nm which are listed in the followingtable:

TABLE 1 Fabric Coated With Inventive Latex Uncoated Fabric SampleWavelength (nm) Absorbance Wavelength (nm) Absorbance 300 1.8094 3000.6326 301 1.8383 301 0.5792 302 1.8253 302 0.5495 303 1.7990 303 0.5062304 1.8127 304 0.4646 305 1.8350 305 0.4238 306 1.7826 306 0.873  3071.8077 307 0.3453 308 1.7943 308 0.3214 309 1.7921 309 0.2885 310 1.8306310 0.2675 311 1.7964 311 0.2505 312 1.7619 312 0.2395 313 1.7981 3130.2258 314 1.7669 314 0.2162 315 1.8006 315 0.2061 316 1.8177 316 0.2014317 1.8032 317 0.1901 318 1.8311 318 0.1901 319 1.8494 319 0.1880 3201.8396 320 0.1850 321 1.8803 321 0.1849 322 1.8396 322 0.1769 323 1.8802323 0.1752 324 1.8698 324 0.1761 325 1.9143 325 0.1762 326 1.9399 3260.1759 327 1.9243 327 0.1763 328 1.9465 328 0.1718 329 1.9402 329 0.1653330 1.9597 330 0.1673 331 1.9699 331 0.1658 332 1.9709 332 0.1676 3331.9779 333 0.1616 334 1.9789 334 0.1597 335 2.0044 335 0.1592 336 1.9877336 0.1554 337 1.9968 337 0.1577 338 2.0020 338 0.1571 339 1.9725 3390.1533 340 1.9881 340 0.1536 341 2.0247 341 0.1529 342 1.9883 342 0.1530343 1.9937 343 0.1495 344 1.9928 344 0.1510 345 1.9746 345 0.1456 3461.9909 346 0.1474 347 1.9807 347 0.1480 348 1.9709 348 0.1425 349 1.9863349 0.1440 350 1.9728 350 0.1420 351 1.9439 351 0.1395 352 1.9671 3520.1382 353 1.9662 353 0.1360 354 1.9451 354 0.1378 355 1.9322 355 0.1343356 1.9191 356 0.1321 357 1.9260 357 0.1329 358 1.9074 358 0.1289 3591.9035 359 0.1270 360 1.8992 360 0.1304 361 1.8958 361 0.1274 362 1.8625362 0.1218 363 1.8728 363 0.1206 364 1.8675 364 0.1247 365 1.8481 3650.1195 366 1.8329 366 0.1193 367 1.7996 367 0.1198 368 1.8203 368 0.1144369 1.7960 369 0.1156 370 1.7782 370 0.1152 371 1.7533 371 0.1164 3721.7361 372 0.1107 373 1.7070 373 0.1096 374 1.6831 374 0.1093 375 1.6565375 0.1022 376 1.6549 376 0.1021 377 1.6329 377 0.1071 378 1.6316 3780.1018 379 1.6049 379 0.1006 380 1.6103 380 0.1010 381 1.5887 381 0.0993382 1.5721 382 0.0974 383 1.5695 383 0.0975 384 1.5596 384 0.0935 3851.5491 385 0.0951 386 1.5544 386 0.0950 387 1.5404 387 0.0915 388 1.5472388 0.0911 389 1.5441 389 0.0920 390 1.5513 390 0.0926 391 1.5398 3910.0908 392 1.5512 392 0.0924 393 1.5475 393 0.0911 394 1.5583 394 0.0898395 1.5554 395 0.0892 396 1.5490 396 0.0902 397 1.5520 397 0.0892 3981.5610 398 0.0883 399 1.5532 399 0.0857 400 1.5542 400 0.0825

The maximum UV absorbance for the inventive latex was measured atbetween about 338 and 341 nm. Clearly, the coating of the subject fabricwith the inventive latex provided a significant improvement in UVabsorbance (and thus decrease in UV transmittance which in turn resultsin a high UPF).

EXAMPLE 4

Latices A and B from EXAMPLE 2 were then each coated on non-woven 0.19dpf polyester fabric swatches previously coated with coagulatedpolyurethane, dried, and tested for colorlightfastness in accordancewith The Engineering Society for Advancing Mobility Land Sea air andSpace Textile Test method SAE J-1885, “(R) Accelerated Exposure ofAutomotive Interior Trim Components Using a Controlled Irradiance WaterCooled Xenon-Arc Apparatus.”. Colorlightfastness is generally calculatedby the following equation:

ΔE*=((L* _(initial) −L* _(exposed))²+(a* _(initial) −a* _(exposed))²+(b*_(initial) −b* _(exposed))²)^(½)

wherein ΔE* represents the difference in color between the fabric uponinitial latex coating and the fabric after the above-noted degree ofultra violet exposure. L*, a*, and b* are the color coordinates; whereinL* is a measure of the lightness and darkness of the colored fabric; a*is a measure of the redness or greenness of the colored fabric; and b*is a measure of the yellowness or blueness of the colored fabric. LatexB showed a lower degree of colorlightfastness (ΔE* of 2.64) than Latex A(ΔE*=3.63). Thus, Latex B exhibited excellent colorlightfastnesscharacteristics while Latex A demonstrated a lower degree ofcolorlightfastness. However, Latex A still showed very beneficialoverall characteristics, particularly in comparison with the control,uncoated fabric (ΔE*=6.20).

EXAMPLE 5

A series of polymers were made following the procedure described inEXAMPLE 1, but the weight ratio of Norbloc™ 7966/butyl methacrylate wasvaried by adjusting the addition rate of each monomer during a batchemulsion polymerization procedure. The surface tension of each polymerwas adjusted as described in EXAMPLE 2. The resulting latices weredip/squeeze applied at 4% solids addition level to a nonwoven polyester(of the type fabric used in EXAMPLE 4) and dried. The coated fabricswere tested for colorlightfastness after 225 kJ/m² exposure (SAEJ-1885). The latices with 40:60 and 35:65 monomer ratios showed the bestcolorfastness performance, in consideration of the cost of the UVmonomer, as noted in the table below.

TABLE 2 Ratio of UV comonomer % of to vinyl-functional monomer LatexSolids ΔE* at (in parts by weight) (owf) 225 kJ/m² 85:15 1.7 3.30 85:153.4 2.30 70:30 1.7 2.90 70:30 3.4 2.10 55:45 1.9 2.00 55:45 3.7 1.8050:50 1.7 2.37 50:50 3.3 1.50 40:60 1.8 2.36 40:60 3.5 1.13 35:65 1.82.83 35:65 3.0 1.57 30:70 1.7 3.00 30:70 3.5 1.60 25:75 1.7 3.36 25:753.9 2.37 20:80 1.9 2.80 20:80 3.4 3.06 10:90 1.8 3.13 10:90 3.8 2.62(Comparative) 100:0 1.8 4.50 (Comparative) 100:0 3.4 3.80

EXAMPLE 6

The nowoven polyester of EXAMPLE 4 was coated with a UV absorbingpolymer latex described in EXAMPLE 4 with a dip/squeeze applicationmethod and dried. Half of the sample was then processed further with asupersonic air treatment (SSAT) pursuant to U.S. Pat. No. 4,837,902, toDischler, previously entirely incorporated by reference at ˜25 ypm.Three runs were made for these fabrics and the colorlightfastnesses arelisted in the following TABLE 2:

TABLE 3 ΔE* (225 kJ/m²) Run # Polymer Latex Amount (owf) without SSATwith SSAT 1 2.9 3.88 2.83 5.0 3.54 1.95 2 3.1 4.96 2.79 5.6 3.59 2.52 32.8 4.63 2.70 4.9 4.50 1.93

Clearly, the greater the amount of latex on the fabric surface, thebetter the colorlightfastness. Furthermore, it is evident that thetreatment by SSAT provides improved colorlightfastness as well.

EXAMPLE 7

A batch polymerization was used to investigate the effects of the chaintransfer agent, 1-dodecanethiol, on the performance of the UV-absorbingpolymer latices. The reactor was a three-neck flask with a temperatureprobe, nitrogen inlet, and condenser/nitrogen outlet. The followingmaterials were charged to the flask and stirred on a hot-plate stirrer:10 g. Norbloc™ 7966 (Janssen), 10 g. butyl methacrylate (Aldrich), 8 g.Abex™ EP-120 (Rhône Poulenc), 2 g. Triton™ X-705 (Union Carbide), 2 g.Synfac® 8216 (Milliken Chemical), 68 g. distilled water, and1-dodecanethiol (Aldrich). The temperature was raised to 75° C. untilthe solids were dispersed uniformly and then lowered to 65° C. forpolymerization. The reactor was purged nitrogen for 30 minutes. Toinitiate the polymerization, 1 ml. of a 0.05 g VA-086 (Wako) and 0.05g/3 ml. water of V-50 (Wako) was introduced into the flask. Anopalescent-white emulsion resulted after 4 hours of reaction. Theresultant latex was again tested from colorlightfastness at 225 kJ/m²,in accordance with SAE J-1885 Test Method. A preferred range ofconcentration of 1-dodecanethiol was from about 0.008 to about 0.018%g./g. monomer was determined, with an optimum amount predicted as beingabout 0.0175% g./g. monomer.

TABLE 4 % Solids (owf) ΔE* at 225 kJ/m² % g. 1-dodecanethiol/g. monomer2.4 3.27 0.002 4.7 2.59 0.002 2.6 2.88 0.005 5.2 2.36 0.005 2.2 2.700.008 4.6 2.46 0.008 2.4 2.63 0.012 4.9 2.00 0.012 2.2 3.81 0.018 4.62.86 0.018 2.3 3.44 0.025 5.0 2.56 0.025 2.6 3.61 0.030 4.8 3.18 0.0302.2 5.18 0.050 4.8 4.26 0.050 (Comparatives) 1.8 5.12 0 3.8 3.61 0

EXAMPLE 8

Selected polyester fabrics were coated with UV-absorbing polymer latices(50/50 wt. ratio Norbloc™ 7966/butyl methacrylate) described in EXAMPLE1 and exposed to SAE J-1885 colorlightfastness testing. The results showthe improved lightfastness of the coated fabrics and are tabulatedbelow:

TABLE 5 Amount of Latex Fabric (% owf; ΔE at X kJ/m² Type manner ofapplication) 225 451 676 901 A 0%  (control) 2.25 4.27 * * A 0.6%; spraycoated 1.93 3.42 * * A 1.3%; spray coated 1.45 2.86 * * B 0%  (control)1.73 3.29 * * B 0.91%; spray coated 1.23 2.56 * * C 0%  (control)3.82 * * * C 0.62%; spray coated 2.99 * * * C 0.83%; spray coated2.86 * * * D 0%  (control) 2.04 3.28 * * D 0.71%; spray coated 1.222.29 * * E 0%  (control) 6.87 * * * E 1.45%; spray coated 4.17 * * * F0%  (control) 0.56 1.20 2.13 3.61 F 5.1%; dip/squeeze applied 0.51 0.741.26 2.37 G 0%  (control) 1.19 2.82 4.97 7.27 G 5.6%; dip/squeezeapplied 1.27 1.70 2.02 3.20 H 0%  (control) 3.89 6.23 * * H 0.66%; spraycoated 2.06 3.76 * * I 0%  (control) 2.83 6.57 * * I 0.70%; spray coated1.01 2.71 * * J 0%  (control) 3.42 6.01 * * J 0.50%; spray coated 1.713.28 * * K 0%  (control) 6.20 * * * K 1.5%; dip/squeeze applied2.55 * * * K 3.3%; dip/squeeze applied 1.18 * * * * The high kJ/m²measurements were taken only for knit fabrics.

The above-listed fabrics were as follows:

A—Woven fabric including 50 denier nylon yarns and weighing 1.360 poundsper yard (greige)

B—Woven fabric including 600 denier nylon fibers and weighing 0.841pounds per yard (greige)

C—Woven fabric including 500 denier polyester yarns and weighing 1.475pounds per yard (greige)

D—Woven fabric including 450 denier nylon fibers and weighing 1 poundper yard (greige)

E—Woven fabric including 450 denier polyester ring-spun yarn weighing1.380 pounds per yard (greige)

F—Knit fabric having 18 warps per inch and weighing 3.70 ounces persquare yard

G—Knit fabric having 20 warps per inch and weighing 5.20 ounces persquare yard

H—Woven fabric having 1684 warp ends and weighing 1.3285 pounds per yard(greige)

I—Woven fabric including nylon fibers having a greige fabric weight of1.102 pounds per yard

J—Woven fabric including 150 denier nylon and weighing 0.7288 pounds peryard (greige)

K—The fabric utilized in EXAMPLE 4, above

These results clearly indicate the improvement in lightfastness accordedthe sample fabrics upon coating with the inventive polymer latex.

EXAMPLE 9

The polymer latex of EXAMPLE 1 was also applied by dip/squeeze techniqueto a greige 100% cotton sample comprised of warp ring-spun yarn and openend spun fill yarn, dyed khaki. This sample was tested for UV-A and UV-Btransmittance. The results were as follows:

TABLE 6 Transmittance Amount of latex (% owf) UV-A UV-B 0% (control)3.6% 1.6% 1.7% 1.1% 0.4% 4.0% 0.8% 0.3%

Clearly, the presence of the inventive latex provided a significantimprovement in UV transmittance (and thus a better UPF for cotton whichgenerally possesses unsatisfactory Ultraviolet Protection Factors).

EXAMPLE 10 (Comparative)

A UV-absorbing polymer emulsion with a 25 wt. % Norbloc™ 7966/75 wt. %butyl methacrylate ratio was prepared as described in EXAMPLE 4. Thelatex was sprayed on the same type of fabric as utilized in EXAMPLE 4,above, and dried. Secondly, a conventional UV absorber, Cibafast® P(Ciba) was also sprayed on the same type of fabric and dried. Thesamples were tested according to Test Method SAE J-1885 after 225 and451 KJ/m² exposure. The inventive UV-absorbing polymer latex providedoverall better colorlightfastness as noted in the table below:

TABLE 7 ΔE* at X kJ/m² Sample 225 451 0% Latex (control) 4.5 7.8 2%(owf) of the inventive latex (spray coated) 3.1 5.4 2% (owf) ofCibafast ® P (spray coated) 4.0 6.7

There are, of course, many alternative embodiments and modifications ofthe present invention which are intended to be included within thespirit and scope of the following claims.

What we claim is:
 1. A method of making an ultraviolet absorbingcopolymer latex by emulsion polymerization comprising mixing together,in the presence of at least one polymerization initiator and at leastone chain transfer agent, (a) at least one vinyl-functional monomerhaving at least one ultra violet absorbing functionality selected fromthe group consisting of benzotriazole, benzophenone, and mixturesthereof; and (b) at least one vinyl-functional monomer not comprising abenzotriazole or benzophenone group; wherein said chain transfer agentis present in an amount of from about 0.002 to 0.050% by weight of thetotal aggregate amount of the UV-absorbing monomer and thevinyl-fiunctional monomer.
 2. The method of claim 1 wherein saidUV-absorbing comonomer is selected from the group consisting of2-hydroxy-5-acrylyloxyphenyl-2H-benzotriazole,1-(3-benzotriazol-2-yl-4-hydroxyphenyl)-ethyl ester acrylic acid,2-(2-methacryloxy-5′-methylphenyl) benzotriazole,2-hydroxy-4-acrylyloxyethoxy benzophenone, and any mixtures thereof;said vinyl-functional monomer is selected from the group consisting ofacrylates and methacrylates, and any mixtures thereof.
 3. The method ofclaim 2 wherein the UV-absorbing comonomer is2-Hydroxy-5-acrylyloxyphenyl-2H-benzotriazole; said vinyl-functionalcomonomer is selected from the group consisting of butyl acrylate,methyl methacrylate, butyl methacrylate, ethyl-hexyl methacrylate,lauryl methacrylate, isodecyl methacrylate, n-hexyl methacrylate, andany mixtures thereof; said UV-absorbing monomer and saidvinyl-functional comonomer are present in weight ratio amounts of fromabout 25:75 to about 60:40.
 4. The method of claim 3 wherein said vinylfunctional comonomer is butyl methacrylate; said UV-absorbing monomerand said vinyl functional comonomer are present in weight ratio amountsof from about 25:75 to about 50:50; and said chain transfer agent ispresent in an amount from about 0.008 to about 0.018% by weight of thetotal aggregate amount of the UV-absorbing monomer and the vinylfunctional comonomer.
 5. The method of claim 3 wherein said UV-absorbingmonomer and said vinyl functional comonomer are present in a weightratio amount of about 35:65; and said chain transfer agent is1-dodecanethiol and is present in an amount of about 0.0175% by weightof the total aggregate amount of the UV-absorbing monomer and the vinylfunctional comonomer.
 6. An article comprising the polymer latexproduced by the method of claim
 1. 7. An article comprising the polymerlatex produced by the method of claim
 2. 8. An article comprising thepolymer latex produced by the method of claim
 3. 9. An articlecomprising the polymer latex produced by the method of claim
 4. 10. Anarticle comprising the polymer latex produced by the method of claim 5.11. A fabric article comprising the polymer latex produced by the methodof claim 1, wherein said fabric comprises fibers selected from the groupconsisting of cotton, polyester, nylon, wool, ramie, lycra, and anymixtures or blends thereof.
 12. A fabric article comprising the polymerlatex produced by the method of claim 2, wherein said fabric comprisesfibers selected from the group consisting of cotton, polyester, nylon,wool, ramie, lycra, and any mixtures or blends thereof.
 13. A fabricarticle comprising the polymer latex produced by the method of claim 3,wherein said fabric comprises fibers selected from the group consistingof cotton, polyester, nylon, wool, ramie, lycra, and any mixtures orblends thereof.
 14. A fabric article comprising the polymer latexproduced by the method of claim 4, wherein said fabric comprises fibersselected from the group consisting of cotton, polyester, nylon, wool,ramie, lycra, and any mixtures or blends thereof.
 15. A fabric articlecomprising the polymer latex produced by the method of claim 5, whereinsaid fabric comprises fibers selected from the group consisting ofcotton, polyester, nylon, wool, ramie, lycra, and any mixtures or blendsthereof.
 16. An article according to claim 11 wherein said fabric issubjected to supersonic air treatment subsequent to the introduction ofthe polymer latex onto the fabric surface.
 17. An article according toclaim 12 wherein said fabric is subjected to supersonic air treatmentsubsequent to the introduction of the polymer latex onto the fabricsurface.
 18. An article according to claim 13 wherein said fabric issubjected to supersonic air treatment subsequent to the introduction ofthe polymer latex onto the fabric surface.
 19. An article according toclaim 14 wherein said fabric is subjected to supersonic air treatmentsubsequent to the introduction of the polymer latex onto the fabricsurface.
 20. An article according to claim 16 wherein said fabric issubjected to supersonic air treatment subsequent to the introduction ofthe polymer latex onto the fabric surface.